Mental toughness plays a critical role in achieving fitness success, as it involves resilience and the ability to push through challenges. Individuals with strong mental toughness can overcome obstacles, maintain motivation, and stick to their fitness routines despite setbacks or difficulty. This psychological attribute helps in developing discipline and focus, enabling one to set and achieve goals. Additionally, mental toughness encourages individuals to embrace discomfort during workouts, thus leading to significant improvements in physical performance over time.